Aha, you've posted a bird very familiar to me, this week! :D I love that flight shot.

Now, I noticed the longish feathers on the back and the black tip on the bill, so I had to look up when Great Egrets breed in Australia. Wikipedia [http://en.wikipedia.org/wiki/Eastern_Great_Egret] tells me that in Queensland they breed in December and January. Looks like this one may be getting ready!? And I learned something new today. Thanks!